This invention relates to a polishing sheet for use in grinding, polishing, cutting and otherwise machining metal, lens, semiconductor and liquid crystal substrates and other workpieces.
Prior art polishing sheets are generally classified into polishing sheets, known as grinding stone, obtained by mixing particulate or powdery abrasive grains for grinding, polishing and cutting with a binder and firing the mixture at elevated temperature and polishing sheets obtained by applying a mixture of abrasive grains and a binder onto a support of fabric, paper, film, fiber, non-woven fabric or the like to bind abrasive grains thereon.
All these polishing sheets are used by fixedly securing them to a polishing or grinding tool which can be rotated at a high speed.
All these polishing sheets, however, have the drawback that they do not perform well for polishing or grinding because the instant a high speed rotating polishing sheet is brought into contact with a workpiece, the polishing sheet is sprung off due to the lack of elasticity in a thickness direction. Polishing at a reduced number of revolutions was thus practiced, but this approach was not satisfactory in either polishing efficiency or precision.
As one improvement in this respect, matrixes based on relatively elastic natural rubber or synthetic rubber were sometimes used as a binder for abrasive grains. These matrixes are poor in bond to abrasive grains and heat resistance as a polishing sheet. None of currently available polishing sheets are truly practical.